The goal of the proposed NIAMS Clinical Trial Planning Grant (R34) is to prepare all documents and activities necessary prior to submitting a U01 Clinical Trial Implementation Cooperative Agreement investigating the non-inferiority of biologic joint restoration using large osteochondral allografts (BioJoint) to traditional arthroplasty in the knee. BioJoint is currently approved for use in patients who are aged 55 years or younger, have BMI under 35, are active (or were active prior to joint problems), and have focal full-thickness cartilage defects. Our team has developed and validated technologic and surgical advances for BioJoints that are expanding the indications for this joint restoration option for patients. However, there has never been a head- to-head comparison between the two surgical treatment options for advanced articular cartilage disorders of the knee using a full clinical trial research design. The proposed R34?and future U01?aim to undertake such a comparison, having already completed the necessary basic science, preclinical, clinical, and regulatory components showing safety and efficacy of the materials and procedures. An expert panel will be convened to provide guidance on designing a clinical trial on BioJoint in two patient populations (patients aged 45-55 versus 55-65 years) and indications (uni-compartmental versus total/extensive for traditional and BioJoint techniques) for the ultimate clinical trial design. Preliminary virtual model recruitment will be performed in each age group based on prior patients at our clinic and our potential collaborating sites over the past five years. Additionally, the R34/U01 team will complete a preliminary cost-analysis of per subject costs of the clinical trial procedures, develop materials for the clinical trial?including study protocols, IRB materials, data collection resources, patient education, and investigator brochures?and develop a budget for the U01. At the conclusion of the R34 period a U01 will be submitted in cooperation with NIAMS for a clinical trial that will alter clinical options for patients with advanced cartilage disease, thus affecting health care, policy, and practice.